The proposed research will elucidate biochemical and structural aspects a dimorphic pathogenic fungus, Sporothrix schenckii, that has worldwide distribution and is the causative agent of sporotrichosis in man. The program builds upon publications from this laboratory that document profound differences in the acid phosphatases among different cell type. On standard laboratory culture medium at 20 degrees C, mycelia and conidia (the saprophytic phase in nature) are generated, and gel electrophoresis of extracts reveals two acid phosphatase activity bands. On the same medium, but at 35 degrees C, yeast cells (pathogenic phase) are produced and they have a much more complicated pattern with up to nine electrophoretically-distinct bands. The "isoenzymes" are also distinguished by different responses to inhibitors (NaF, phosphate and tartrate). On a special growth medium we can 'force' yeastlike cells at 20 degrees C, i.e. the reverse' the usual temperature-dependent morphology. Most importantly, we find that these cells have true yeast ultrastructure and exhibit the yeast isoenzyme pattern. Thus an association between isoenzyme pattern and morphology is indicated; and the expression of the acid phosphatase genes is not simply a matter of growth temperature. Preliminary results indicate that acid phosphatase-containing extracts of S. schenckii interfere wit) the production of fungicidal superoxide anion by stimulated human neutrophils. The cascade of events in the latter involves protein phosphorylation. We know that unresolved mixtures of S. schenckii acid phosphatases will dephosphorylate test proteins. Thus there is a need identify the individual isoenzymes that can act on animal phosphoproteins to establish the native substrates of all of the isoenzymes, their subcellular locales, and alterations that attend cell shape transitions; that is the thrust of our proposal which involves enzymology and complementary studies by electron microscopy. In this manner we will define the functions of the isoenzymes, probe their involvement in morphogenesis, explore participation in the disease process. Key results with the working strain will be repeated with freshly-isolated pathogenic strains.